Solid state catholyte or electrolyte for battery using LiaMPbSc (M=Si, Ge, and/or Sn)

ABSTRACT

The present invention provides an energy storage device comprising a cathode region or other element. The device has a major active region comprising a plurality of first active regions spatially disposed within the cathode region. The major active region expands or contracts from a first volume to a second volume during a period of a charge and discharge. The device has a catholyte material spatially confined within a spatial region of the cathode region and spatially disposed within spatial regions not occupied by the first active regions. In an example, the catholyte material comprises a lithium, germanium, phosphorous, and sulfur (“LGPS”) containing material configured in a polycrystalline state. The device has an oxygen species configured within the LGPS containing material, the oxygen species having a ratio to the sulfur species of 1:2 and less to form a LGPSO material. The device has a protective material formed overlying exposed regions of the cathode material to substantially maintain the sulfur species within the catholyte material. Also included is a novel dopant configuration of the Li a MP b S c  (LMPS) [M=Si, Ge, and/or Sn] containing material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/986,675, entitled SOLID STATE CATHOLYTE OR ELECTROLYTE FOR BATTERYUSING LIAMPBSC (M=SI, GE, AND/OR SN), filed May 22, 2018, which is acontinuation of U.S. patent application Ser. No. 15/726,317, entitledSOLID STATE CATHOLYTES AND ELECTROLYTES FOR ENERGY STORAGE DEVICES,filed Oct. 5, 2017, which is a continuation of U.S. patent applicationSer. No. 15/404,179, entitled SOLID STATE CATHOLYTES AND ELECTROLYTESFOR ENERGY STORAGE DEVICES, filed Jan. 11, 2017, which is a divisionalof U.S. patent application Ser. No. 14/849,468, entitled SOLID STATECATHOLYTES AND ELECTROLYTES FOR ENERGY STORAGE DEVICES, filed Sep. 9,2015, which is a continuation of U.S. patent application Ser. No.14/618,979, entitled SOLID STATE CATHOLYTES AND ELECTROLYTES FOR ENERGYSTORAGE DEVICES, filed Feb. 10, 2015, which is a continuation of PCTApplication No. PCT/US2014/038238, filed May 15, 2014, entitled SOLIDSTATE CATHOLYTE OR ELECTROLYTE FOR BATTERY USING Li_(a)MP_(b)S_(c)(M=Si, Ge, and/or Sn), which claims priority to U.S. Provisional PatentApplication No. 61/823,407, filed May 13, 2013, and U.S. ProvisionalPatent Application No. 61/935,956, filed Feb. 5, 2014, the disclosuresof which are incorporated herein by reference in their entirety.

BACKGROUND

In some examples, an embodiment of the present invention relatesgenerally to a solid catholyte or electrolyte material having desiredion conductivity. More particularly, an embodiment of the presentinvention provides a method and structure for a catholyte material toimprove a total ionic conductivity for a cathode to allow for highermass loading of an active material, faster charge/discharge, and a widerrange of operating temperature. Merely by way of example, the inventionhas been applied to solid state battery cells, although there can beother applications.

A high level of development has caused an explosion in electronic andcommunication apparatus. As an example, such apparatus include, amongothers, a personal computer, a video camera and a portable telephone,commonly termed a “smart phone.” Examples of popular smart phonesinclude the iPhone™ from Apple Inc. of Cupertino, Calif. or those phonesusing the Android™ operating system of Google Inc. in Mountain View,Calif. Other popular apparatus include electric or hybrid automobilessuch as those from Tesla Motors Inc. in Fremont, Calif. or the Priusmanufactured by Toyota Motor Corporation. Although highly successful,these popular apparatus are limited by storage capacity and inparticular battery capacity. That is, a higher power and higher capacitybattery for an electric automobile or a hybrid automobile would be anadvance in the automobile industry. A lithium battery has been presentlynoticed from the viewpoint of a high energy density among various kindsof batteries.

Liquid electrolyte containing a flammable organic solvent has been usedfor conventional lithium batteries. Liquid electrolytes suffer fromoutgassing at high voltage and pose a threat of thermal runaway due tothe enthalpy of combustion of the solvents. A lithium battery configuredwith a solid electrolyte layer (replacing the liquid electrolyte) hasbeen described to improve the safety of the battery. A sulfide solidelectrolyte material has been known as a solid electrolyte material usedfor a solid-state lithium battery. As an example, a solid electrolytematerial is described in EP2555307 A1 published Feb. 6, 2013, and filedMar. 25, 2011, which claims priority to Mar. 26, 2010, in the names ofRyoji Kanno and Masaaki Hirayama, assigned to Tokyo Institute ofTechnology and Toyota Jidosha Kabushiki Kaisha, which is herebyincorporated by reference.

State of the art solid state batteries are not ready for mass marketadoption due to limited power density, mass loading, andmanufacturability. Accordingly, techniques for improving a solid-statebattery are highly desired.

SUMMARY OF INVENTION

According to an embodiment of the present invention, techniques relatedto a solid catholyte or electrolyte material having desired ionconductivity are provided. More particularly, an embodiment of thepresent invention provides a method and structure for a catholytematerial to improve a total ionic conductivity for a cathode to allowfor higher mass loading of an active material, faster charge/discharge,and a wider range of operating temperature. Merely by way of example,the invention has been applied to solid state battery cells, althoughthere can be other applications.

In an example, an embodiment of the present invention provides an energystorage device comprising a cathode region or other element. The devicehas a major active region comprising a plurality of first active regionsspatially disposed within the cathode region. The major active regionexpands or contracts from a first volume to a second volume during aperiod of a charge and discharge. The device has a catholyte materialspatially confined within a spatial region of the cathode region andspatially disposed within spatial regions not occupied by the firstactive regions. In an example, the catholyte material comprises alithium, germanium, phosphorous, and sulfur (“LGPS”) containing materialconfigured in a polycrystalline state. The device has an oxygen speciesconfigured within the LGPS containing material, the oxygen specieshaving a ratio to the sulfur species of 1:2 and less to form a LGPSOmaterial. The device has a protective material formed overlying exposedregions of the cathode material to substantially maintain the sulfurspecies within the catholyte material.

In an alternative example, an embodiment of the present inventionprovides an energy storage device comprising a cathode region or otherelement. The device has a major active region comprising a plurality offirst active regions spatially disposed within the cathode region. Thedevice has a catholyte material spatially confined within a spatialregion of the cathode region and spatially disposed within spatialregions not occupied by the first active regions. In an example, thecatholyte material comprises a lithium, germanium, phosphorous, andsulfur (“LGPS”) containing material or a lithium, silicon phosphorous,and sulfur (“LSPS”) containing material, each of which is configured ina polycrystalline or amorphous state or variations or combinationsthereof. The device has an oxygen species configured within the LGPS orLSPS containing material. The oxygen species has a ratio to the sulfurspecies of 1:2 and less to form a LGPSO or LSPSO material. The devicehas a confinement material formed overlying exposed regions of thecathode active material to minimize reaction between the LGPS or LSPScontaining material and the active material.

In an alternative example, an embodiment of the present inventionprovides an energy storage device comprising a cathode region or otherelement. The device includes a major active region comprising aplurality of first active regions spatially disposed within the cathoderegion, and a catholyte material spatially confined within a spatialregion of the cathode region and spatially disposed within spatialregions not occupied by the first active regions. In an example, each ofthe plurality of active regions has a median diameter ranging from about20 nm to about 3 μm. In another example, each of the plurality of activeregions has a median diameter ranging from about 20 nm to about 8 μm.

In an example, the catholyte material comprises a lithium, germanium,phosphorous, and sulfur (“LGPS”) containing material or a lithium,silicon phosphorous, and sulfur (“LSPS”) containing material, each ofwhich is configured in a polycrystalline or amorphous state. In anexample, the device has a plurality of particles characterizing thecatholyte material. In an example, each of the plurality of particles isinterconnected to another via a necking arrangement. Each particle has adimension characterized by a particle diameter to neck ratio dimensionranging from 1% to greater than 100%. In some examples, the plurality ofparticles is arranged to form a polycrystalline structure having aporosity of less than 30% of a total volume of the cathode region. In anexample, each of the plurality of particles in the catholyte material issubstantially homogeneous in a micro-scale while configured in thepolycrystalline structure in a ten to one hundred micron scale. In anexample, the cathode region comprises an active material, the activematerial comprising iron and fluorine. In an example, the catholytematerial is selected from one of Li_(x)SiP_(y)S_(z) orLi_(a)GeP_(b)S_(c). In an example, the catholyte material is provided byannealing Li₂S, P₂S₅, and GeS₂ or SiS₂ at 550° C. for greater than about4 hrs in stainless steel reactors sealed from the air, or othervariations. In an example, the catholyte material is configured tosubstantially fill the cathode region comprising the major active regionto form a substantially homogeneous thickness of material defining thecathode region. In an example, the catholyte material comprising aplurality of clusters, each of which has a median diameter ranging fromabout 10 nm to about 300 nm. In an example, the catholyte materialcomprising a plurality of shell structures around the cathode activeregions. In an example, the catholyte material configured as a pluralityof particles, each of the particles having a median diameter rangingfrom about 20 nm to about 300 nm. In an example, the catholyte materialis substantially free from oxygen species.

In an example, the oxygen species ranges from less than 1 percent to 20percent of the LGPSO or LSPSO material. In an example, the sulfurcontaining species ranges from about 25 to 60 percent of the LGPSO orLSPSO material. In an example, the device has an oxygen speciesconfigured within the LGPS or LSPS containing material. In an example,the oxygen species has a ratio to the sulfur species of 1:2 and less toform a LGPSO or LSPSO material.

The device has a confinement material formed overlying exposed regionsof the cathode active material to minimize reaction between the LGPS orLSPS containing material and the active material. In an example, theconfinement material is configured as a barrier material and/or theconfinement material substantially preventing an interaction of thesulfur containing species with an element within the major activeregion. In an example, the confinement material is configured toselectively allow a lithium species to traverse through the confinementmaterial. In an example, the major active region is greater than 50percent by volume of the cathode region. The active region is desirablyas great a fraction as possible of the cathode, possibly up to 70% oreven 80%. In an example, the device has a second confinement materialoverlying each of the plurality of active regions.

In an example, the device has a polymer material configured within avicinity of the catholyte material, the polymer material serving as abinder material. In an example, the polymer material is formed overlyingthe catholyte material. In an example, the polymer material serves as anelectrolyte. In an example, the polymer material has an ionicconductivity serves as an electrolyte. In an example, the polymermaterial is configured to accommodate an internal stress within thecathode region during the change in volume from the expansion to acontraction.

In an example, an embodiment of the present invention provides an energystorage device comprising a catholyte material spatially confined withina spatial region of the energy storage device. The material includes alithium, germanium, phosphorous, and sulfur (“LGPS”) containing materialor a lithium, silicon phosphorous, and sulfur (“LSPS”) containingmaterial, each of which is configured in a polycrystalline,nanocrystalline or amorphous state. The device has a room temperatureionic conductivity ranging from 10⁻⁵ to 5×10⁻² S/cm characterizing theLGPS or LSPS material and an electrical conductivity less than 10⁻⁵ S/cmcharacterizing the LGPS or LSPS material.

In an example, an embodiment of the present invention provides an energystorage device comprising a catholyte material spatially confined withina spatial region of the energy storage device. The material has alithium, silicon, phosphorous, and sulfur (“LSPS”) containing material.Each of which is configured in a polycrystalline or amorphous state. Thedevice has a room temperature ionic conductivity ranging from 10⁻⁵ S/cmto 5×10⁻² S/cm characterizing the LSPS material, an electricalconductivity less than 10⁻⁵ S/cm characterizing the LSPS material, andan XRD 2θ scan characterized by a primary peak at 33°±1°, 31°±1°, or43°±1°.

In an example, an embodiment of the present invention provides an energystorage device comprising a cathode region or other region(s). Thedevice has a major active region comprising a plurality of first activeregions spatially disposed within the cathode region. The major activeregion expands or contracts from a first volume to a second volumeduring a period of a charge and discharge. The device has a catholytematerial spatially confined within a spatial region of the cathoderegion and spatially disposed within spatial regions not occupied by thefirst active regions. In an example, the catholyte material comprises alithium, germanium, phosphorous, and sulfur (“LGPS”) containing materialconfigured in a polycrystalline state. The catholyte material ischaracterized by an XRD as measured in counts per second characterizedby a first major peak between about 41 to 45° 2theta (i.e., 2θ) and asecond major peak between about 30 to 35° 2theta and a third major peakbetween 51-54° 2-theta; whereupon the first major peak is higher inintensity than either the second major peak or the third major peak.

In an example, an embodiment of the present invention provides a methodfor manufacturing an energy storage device. The method includes forminga cathode region, the cathode region comprising a major active regioncomprising a plurality of first active regions spatially disposed withinthe cathode region. The major active region expands or contracts from afirst volume to a second volume during a period of a charge anddischarge; a catholyte material spatially confined within a spatialregion of the cathode region and spatially disposed within spatialregions not occupied by the first active regions, the catholyte materialcomprising a lithium, germanium, phosphorous, and sulfur (“LGPS”)containing material configured in a polycrystal line state.

In an example, an embodiment of the present invention provides a solidcatholyte material or other material. The material includes at least alithium element, a silicon element, a phosphorous element, a sulfurelement, and an oxygen element. In an example, the catholyte ischaracterized by a major XRD peak located at a peak position of2θ=30°±1° in an X-ray diffraction measurement using a CuKα line, or apeak of 2θ=33°±1° or a peak of 2θ=43°±1°.

In an alternative example, the invention provides a solid ion conductingmaterial characterized by a formula Li_(a)SiP_(b)S_(c)O_(d) where 2≤a≤8,0.5≤b≤2.5, 4≤c≤12, d<3, wherein any impurities are less than 10 atomicpercent. In an example, the solid ion conducting material comprising Li,Si, P, and S is characterized by primary Raman peaks at 418±10 cm⁻¹,383±10 cm⁻¹, 286±10 cm⁻¹, and 1614±10 cm−1 when measured at roomtemperature with a Renishaw inVia Raman microscope system with a laserwavelength of 514 nm.

In some examples, an embodiment of the present invention achieves thesebenefits and others in the context of known process technology. However,a further understanding of the nature and advantages of an embodiment ofthe present invention may be realized by reference to the latterportions of the specification and attached drawings.

According to an embodiment of the present invention, techniques relatedto a solid catholyte material having desired ion conductivity areprovided. In particular, an embodiment of the present invention providesa method and structure for a catholyte material to improve a total ionicconductivity for a cathode to allow for higher mass loading of an activematerial, faster charge/discharge, and a wider range of operatingtemperature. More particularly, an embodiment of the present inventionprovides a novel dopant configuration of the Li_(a)MP_(b)S_(c) (LMPS)[M=Si, Ge, and, or, Sn] containing material. Merely by way of example,the invention has been applied to solid state battery cells, althoughthere can be other applications. In some examples, M is selected fromSi, Ge, Sn, or combinations thereof. In some other examples, M isselected from Si, Sn, or combinations thereof.

In an example, an embodiment of the present invention provides for asolid state catholyte material to enable a fully solid state batterywith improved total ionic conductivity for a cathode, higher massloading of active material (therefore higher energy density), fastercharge/discharge, and a wider range of operating temperature. The solidstate architecture eliminates the need for a flammable liquidelectrolyte and therefore provides a safer alternative.

In an example, an embodiment of the present invention provides a dopantspecies configured within the LMPS containing material. In an example,the dopant species is characterized by increasing an ionic conductivityof the LMPS material from a first ion conductivity value to a secondionic conductivity value. Such dopant species may be provided in any oneof the examples described below. In an example, an embodiment of thepresent invention provides an energy storage device comprising a cathoderegion or other element. The device has a major active region comprisinga plurality of first active regions spatially disposed within thecathode region. The major active region expands or contracts from afirst volume to a second volume during a period of a charge anddischarge. The device has a catholyte material spatially confined withina spatial region of the cathode region and spatially disposed withinspatial regions not occupied by the first active regions. In an example,the catholyte material comprises a lithium, germanium, phosphorous, andsulfur (“LGPS”) containing material configured in a polycrystallinestate. The device has an oxygen species configured within the LGPScontaining material, the oxygen species having a ratio to the sulfurspecies of 1:2 and less to form a LGPSO material. The device has aprotective material formed overlying exposed regions of the cathodematerial to substantially maintain the sulfur species within thecatholyte material.

In an alternative example, an embodiment of the present inventionprovides an energy storage device comprising a cathode region or otherelement. The device has a major active region comprising a plurality offirst active regions spatially disposed within the cathode region. Thedevice has a catholyte material spatially confined within a spatialregion of the cathode region and spatially disposed within spatialregions not occupied by the first active regions. In an example, thecatholyte material comprises a lithium, germanium, phosphorous, andsulfur (“LGPS”) containing material or a lithium, silicon, phosphorous,and sulfur (“LSPS”) containing material, each of which is configured ina polycrystalline or amorphous state or variations. The material mayhave an oxygen species configured within the LGPS or LSPS containingmaterial. The oxygen species has a ratio to the sulfur species of 1:2and less to form a LGPSO or LSPSO material. The device has a confinementmaterial formed overlying exposed regions of the cathode active materialto minimize reaction between the LGPS or LSPS containing material andthe active material.

In an alternative example, an embodiment of the present inventionprovides an energy storage device comprising a cathode region or otherelement. The device includes a major active region comprising aplurality of first active regions spatially disposed within the cathoderegion, and a catholyte material spatially confined within a spatialregion of the cathode region and spatially disposed within spatialregions not occupied by the first active regions. In an example, each ofthe plurality of active regions has a size ranging from about 20 nm toabout 3 μm.

In an example, the catholyte material comprises a lithium, germanium,phosphorous, and sulfur (“LGPS”) containing material, or a lithium,silicon, phosphorous, and sulfur (“LSPS”) containing material, or alithium, tin, phosphorous, and sulfur (“LTPS”) containing material. Eachof the compounds may be configured in a polycrystalline or amorphousstate. In an example, the device has a plurality of particlescharacterizing the catholyte material. In an example, each of theplurality of particles is interconnected to another via a neckingarrangement. Each particle has a dimension characterized by a neck toparticle diameter ratio dimension ranging from 1% to greater than 100%to form a polycrystalline structure having a porosity of less than 30%of a total volume of the cathode region. In an example, each of theplurality of particles in the catholyte material is substantiallyhomogeneous, or can have variations. For example, the particles can havea diameter ranging from about 20 nm to about 1 micron. In an example,the cathode region comprises an active material, the active materialcomprising iron and fluorine. In an example, the cathode regioncomprises an active material, the active material comprising one or moreof LiFePO₄, LiCoO₂, LiMn₂O₄, LiNi_(x)Mn_(2-x)O₄, Li(NiCoAl)O₂, or otherconventional lithium battery cathode materials. In an example, thecatholyte material is selected from one of Li_(x)SiP_(y)S_(z) orLi_(a)GeP_(b)S_(c). In an example, the catholyte material is provided byannealing Li₂S, P₂S₅, and GeS₂ or SiS₂ at 550° C. for greater than about4 hrs in stainless steel reactors sealed from the air, or othervariations. In an example, the catholyte material is configured tosubstantially fill the cathode region comprising the major active regionto form a substantially homogeneous thickness of material defining thecathode region. In an example, the catholyte material comprising aplurality of clusters, each of which has a diameter ranging from about10 nm to about 300 nm. In an example, the catholyte material comprisinga plurality of shell structures around the cathode active regions. In anexample, the catholyte material configured as a plurality of particles,each of the particles having a diameter ranging from about 20 nm toabout 300 nm. In an example, the catholyte material is substantiallyfree from oxygen species.

In an example, the oxygen species ranges from less than 1 percent to 20percent of the LGPSO or LSPSO material. In an example, the sulfurcontaining species ranges from about 25 to 60 percent of the LGPSO orLSPSO material. In an example, the device has an oxygen speciesconfigured within the LGPS or LSPS containing material. In an example,the oxygen species has a ratio to the sulfur species of 1:2 and less toform a LGPSO or LSPSO material.

In an example, the LMPS material is doped with a combination of metalspecies on the M site. The composition range includesLi_(a)(SiSn)P_(b)S_(c) (“LSTPS”), Li_(a)(SiGe)P_(b)S_(c),Li_(a)(GeSn)P_(b)S_(c), and Li(SiGeSn)P_(b)S_(c), including variationsin a ratio of Si to Sn, and other alternatives. The material may have anoxygen species configured within the LSTPS, LSGPS, LGTPS, or LSGTPScontaining material to form LSTPSO, LSGPSO, LGTPSO, or LSGTPSO. Theoxygen species has a ratio to the sulfur species of 1:2 and less.

In an example, the device has a confinement material formed overlyingexposed regions of the cathode active material to minimize reactionbetween the LGPS or LSPS containing material and the active material. Inan example, the confinement material is configured as a barrier materialand/or the confinement material substantially preventing an interactionof the sulfur containing species with an element within the major activeregion. In an example, the confinement material is configured toselectively allow a lithium species to traverse through the confinementmaterial. In an example, the major active region is greater than 50percent by volume of the cathode region. The active region is desirablyas great a fraction as possible of the cathode, possibly up to 70% oreven 80%. In an example, the device has a second confinement materialoverlying each of the plurality of active regions.

In an example, an embodiment of the present invention achieves thesebenefits and others in the context of known process technology. However,a further understanding of the nature and advantages of an embodiment ofthe present invention may be realized by reference to the latterportions of the specification and attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified diagram illustrating mixing cathode activematerial with catholyte to improve overall ion conductivity according toan example of an embodiment of the present invention.

FIG. 2 is a simplified diagram illustrating mixing smaller particles ofcatholyte with active cathode material for enhancing ionic andelectronic conductivity according to an example of the presentinvention.

FIGS. 3 and 3A are a simplified diagram illustrating a cross-section ofa battery device according to an example of the present invention.

FIG. 4 is a simplified diagram illustrating LSPS ionic and electronicconductivity Arrhenius plot according to an example of the presentinvention.

FIG. 5 shows SEM of LSPS, LGPS, illustrating a necking behavior andforming connecting networks according to an example of the presentinvention.

FIG. 6 shows LSPS XRD scan in air and peak location derived frommaterial that is crystalline from the annealing process according to anexample of the present invention.

FIG. 7 shows an XRD pattern. & peak positions of LSPS taken in an argonenvironment according to an example of the present invention.

FIG. 8 shows an LSPS XPS scan and stoichiometry including LSPS specificpeak shifts according to an example of the present invention.

FIG. 9 shows XRD patterns and peaks of several LGPS powders taken in anargon atmosphere according to an example of the present invention.

FIG. 10 shows a cyclic voltammogram of LGPS using a lithiumreference/counter electrode and stainless steel working electrodeaccording to an example of the present invention.

FIG. 11 shows an illustration of Raman spectroscopy signatures ofseveral LGPS samples according to an example of the present invention.

FIG. 12 shows an illustration of Raman spectroscopy of LGPS, comparingto precursors according to an example of the present invention.

FIG. 13 shows an illustration of an LGPS ionic conductivity Arrheniusplot according to an example of the present invention.

FIG. 14 shows LGPS ionic conductivity as a function of P and Geconcentrations according to an example of the present invention.

FIG. 15 shows composition of P and Ge in pressed pellets ofLi_(a)GeP_(b)S_(c) measured by X-ray photoelectron spectroscopy (XPS) asa function of Li₂S:P₂S₅:GeS₂ precursor ratio.

FIG. 16 shows ion conductivity plotted as a function of temperature forsamples according to an embodiment of the present invention.

FIG. 17 shows an XRD spectrum of an LSPS sample with conductivity of9e-4 S/cm at 30° C.

FIG. 18A is a simplified illustration of an electrode material(including an active positive electrode material, ionic conductor, andelectronic conductor) according to an example of the present invention;

FIG. 18B is a simplified illustration of a negative electrode currentcollector, a solid state electrolyte, and a positive electrode currentcollector according to an example of the present invention;

FIG. 19 illustrates ionic conductivity at 60° C. of LGPS, LSPS, LSTPS,and LTPS according to examples of the present invention.

FIG. 20 illustrates an Arrhenius plot of ionic conductivity foractivation energies are as follows: LGPS—0.21 eV. LSTPS—0.25 eV.LSPS—0.28 eV. LTPS—0.26 eV, in various examples according to the presentinvention.

FIG. 21 illustrates crystal structure from XRD spectra of LSTPS, LSPS,and LTPS according to examples according to the present invention.

FIGS. 22A, 22B, 22C, and 221D are examples of ⁷Li NMR plots.

FIGS. 23A, 23B, 23C, and 23D are examples of ³¹P NMR plots.

FIG. 24 illustrates a schematic of full cell with solid state catholytein an example according to the present invention.

FIG. 25 is a SEM micrograph of cast film of solid state catholyteaccording to an example of the present invention.

DETAILED DESCRIPTION OF THE SPECIFIC EMBODIMENTS

According to an embodiment of the present invention, techniques relatedto a solid catholyte or electrolyte material having desired ionconductivity are provided. More particularly, an embodiment of thepresent invention provides a method and structure for a catholytematerial to improve a total ionic conductivity for a cathode to allowfor higher mass loading of an active material, faster charge/discharge,and a wider range of operating temperature. Merely by way of example,the invention has been applied to solid state battery cells, althoughthere can be other applications.

As background, poor ionic conductivity of the cathode in a batteryimposes strong limitations to overall performance. By mixing the lowionic conductivity cathode active material with a high ionicconductivity ceramic catholyte, it is possible to improve the overallcathode conductivity. In this description, the ceramic catholyte iseither LGPS or LSPS, which possesses Li ion conductivity greater than1e-3 S/cm at 60° C. An overall ion conductivity of the cathode (1e-4S/cm) can be achieved by adjusting the volume ratio of the activecathode material (ranging from about 30% to about 85%) to the catholyte.To improve electronic conductivity to match the ionic conductivity,carbon can be added as a third component or pre-coated onto the cathodeactive material.

In an example, the composition of the catholyte is Li_(a)XP_(b)S_(c),where X=Ge (for LGPS) or Si (for LSPS). LGPS and LSPS are synthesizedusing similar starting materials: Li₂S, P₂S₅, and GeS₂ or SiS₂. Thesynthetic approach includes ball milling of the precursors to create ahomogenous mixture, followed by annealing at 550° C. in an air-tightvessel, and additional ball milling of the resultant product to achievethe desired particle size. Alternatively, the material can be made byevaporating the pre-annealed powder or co-evaporating Li₂S, P₂S₅, andSiS₂/GeS₂ powders. As a thin film, the compounds could also be used aselectrolytes.

LSPS as described herein can be used as a thin film electrolyte. Meansto deposit LSPS as a thin film are known to those skilled in the art. Asan example, PVD methods such as PLD, sputtering, thermal, e-beam, and/orflash evaporation can be used. As a specific, non-limiting example ofone deposition by thermal evaporation, the process is as follows: 1.Clean a smooth stainless steel substrate (430 alloy) with a kitchensponge and simple green. Rinse in water. Rinse in acetone. Rinse inwater. Microwave for two minutes submerged in water. 2. Load substrateinto evaporator. 3. Prepare LSPS material as described above and pressLSPS in the ratio of 5:1:1 Li₂S:P₂S₅:SiS₂ into pellets. Load pelletsinto evaporator crucible. Total mass of LSPS is 1.5 g. 4. Pumpevaporator down to base pressure of ˜1e-5 torr. 5. Evaporate for 23minutes with heater at ˜1400 degrees C. while rotating substrate. 6.Purge evaporator twice with inert gas. 7. Evaporate inert metal, e.g. Ptor Au, as top contact.

In an example, a benefit of replacing Ge with Si is to address the highcost of Ge, among others. The price Ge is approximately 800 times of Si.The overall material cost of the catholyte drops by a factor of 10 if Geis replaced with Si. Use of Si in place of Ge also appears to improvethe stability of the material interface to Li. Further details of anembodiment of the present invention can be found throughout the presentspecification and more particularly below.

As used herein, the phrase “substantially free from oxygen species,”refers to a material having less than 5% oxygen.

As used herein, the phrase “substantially prevent,” refers to materialwherein the catholyte or cathode active material do not react to form aseparate phase that prevents a long cycle life, wherein a long cyclelife is characterized by greater than 100 cycles. If the catholyte orcathode active material substantially react, e.g., more than 1% massfraction of the active material reacts, to form a separate phase that isnot useful for battery performance, the cycle life of the cathode or ofthe battery is shortened. As such, the battery cycle life is maintainedat a long cycle life (>100 cycles) when the catholyte or cathode activematerial do not substantially react to form a detrimental separatephase.

As used herein, the phrase “substantially homogeneous thickness,” refersto a material having a roughness of less than 1 micron.

As used herein, the phrase “substantially free from oxygen” refers to amaterial having less than 5% oxygen.

As used herein, the phrase “selectively allow a lithium species totraverse through the material,” refers to material that allows lithiumspecies to diffuse therethrough by at least 7 or 8 orders of magnitudemore than another diffusion species. As used herein, “selectively allow”also refers to >C/3 rate capability for charge/discharge with lithiumwhile providing for long (>100 cycles) cycle life.

Active material mass loading in a cathode determines the energy densityof a battery. Increasing the accessible active material mass loading persurface area improves the overall system energy density by increasingthe ratio of active material to inactive components including currentcollectors and separators. The active material mass loading is limitedby the total ionic and electronic conductivity through the cathode. Byincluding a high Li⁺ ionic conductivity catholyte in the cathode,lithium access is improved throughout the entire cathode thickness andreduces voltage losses to overpotential. The use of ceramic materialalso may reduce/eliminate the formation of a solid electrolyte interface(SEI) and provide a wider voltage stability window.

FIG. 1 is a simplified diagram illustrating mixing cathode activematerial with catholyte (MEIC) to improve overall ion conductivityaccording to an example of the present invention. As shown, mixingoccurs with active material, which can be any suitable active materialwith catholyte material, which can be Li_(a)XP_(b)S_(c), where X=Ge (forLGPS) or Si (for LSPS), and combinations thereof, or the like. As shown,the catholyte material is coated or configured around or within avicinity of the active material. As shown is a core shell structure,although there can be variations. The core-shell structure may befabricated by solid-state synthesis such as co-milling or mechanofusion,liquid phase synthesis such as precipitation or heterogeneous reaction,or vapor phase synthesis such as CVD or evaporation. In an example, thepresent catholyte material has a high ion conductivity of 10⁻¹ S/cm andgreater.

FIG. 2 is a simplified diagram illustrating mixing smaller particles ofMEIC with active cathode material in the ideal geometry for enhancingionic and electronic conductivity according to an example of the presentinvention. As shown, smaller particles of MEIC are mixed with activecathode material to form a plurality of clusters representing intermixedactive cathode material spatially disposed with the MEIC particles. Inanother example, the illustration shows engineered sized catholyteparticles to improve and or to optimize ion conductivity to form apercolating network structure.

FIG. 3 is a simplified diagram illustrating a cross-section of a batterydevice according to an example of the present invention. As shown, thebattery device comprises an anode region, a first current collector, anelectrolyte, a second current collector, and a cathode region. Furtherdetails of battery device can be found throughout the presentspecification and more particularly below, and also in reference to FIG.3A.

In an example, the anode region comprises a major active regioncomprising lithium. The anode region has a thickness ranging from about0.1 μm to about 100 μm, but can include variations. In an embodiment,the anode region is created in situ by plating lithium from the cathodeduring the first charging cycle, among other techniques.

Each of the current collectors is a metal foil or a metal coating. Eachcurrent collector has a major surface region and preferably has athickness ranging from 100 nm to 25 μm, although there may bevariations. In an example, the negative current collector is a foil madeof copper, nickel, nickel-coated copper, iron-coated copper,copper-coated aluminum, titanium, stainless steel, and coatings of theseand other materials known not to alloy with lithium, and configured tothe anode region. In another example, the positive current collector isaluminum foil or carbon-coated aluminum foil, though other materialsstable at >3.5V vs Li (either intrinsically or via a self-passivatingmechanism) can be used. The positive current collector is configured tothe cathode region. In the case that one or both current collectors is ametal coating rather than a foil, it may be created with standard routessuch as electroplating, electroless plating, PVD, metal nanoparticlesintering, and/or sol-gel with post-reduction. In this example,configured includes adhering or bonding the current collector to thatwhich it is configured.

As shown, the battery device has an electrolyte. The electrolyte is, insome examples, a fast lithium ion conductor with a conductivity ofgreater than 10⁻⁵ S/cm. Examples of such materials include garnet,LiPON, antiperovskite, LISICON, thio-LISICON, sulfide, oxysulfide,polymer, composite polymer, ionic liquid, gel, or organic liquid. Theelectrolyte has a thickness ranging from about 0.1 μm to about 40 μm,but includes variations. In some examples, the electrolyte thickness is25 μm, i.e., 25 microns. In some examples, the electrolyte thickness is25 μm or less, i.e., 25 microns or less.

In an example, the cathode region comprises a major active regioncomprising a plurality of first active regions spatially disposed withinthe cathode region. The cathode region includes a catholyte materialspatially confined within a spatial region of the cathode region. In anexample, the material is spatially disposed within spatial regions notoccupied by the active regions, the catholyte material comprising alithium, germanium, phosphorous, and sulfur (“LGPS”) containing materialor a lithium, silicon, phosphorous, and sulfur (“LSPS”) containingmaterial, each of which is configured in a polycrystalline or amorphousstate. The catholyte material has an ion conductivity greater than 10⁻⁴S/cm and preferably greater than 10⁻³ S/cm. The catholyte material isconfigured to form a percolating network through the cathode. Thecatholyte material is therefore made with a particle size that issmaller than the active region particle size. For example, the mediancatholyte particle can be have a diameter three times or more smallerthan the median active particle size. The particle size may be measuredby techniques familiar to those skilled in the art such as a Horibaparticle size analyzer. The catholyte material may alternately beconfigured in a core-shell structure as a coating around the cathodeactive material. In a further variation, the catholyte material may beconfigured as nanorods or nanowires. The cathode is then densified, forexample in a calendar press, to reduce porosity, thereby increasing thedensity of the cathode.

The cathode region also includes electronically conducting species suchas carbon, activated carbon, carbon black, carbon fibers, carbonnanotubes, graphite, graphene, fullerenes, metal nanowires, super P, andother materials known in the art. The cathode region further comprises abinder material to improve the adhesion of the cathode to the substrateand the cohesion of the cathode to itself during cycling.

In an example, the catholyte material has an oxygen species configuredwithin the LGPS or LSPS containing material. In an example, the oxygenspecies has a ratio to the sulfur species of 1:2 and less to form aLGPSO material or LSPSO material. In an example, the oxygen species isless than 20 percent of the LGPSO material. Of course, there can bevariations which are embraced by other embodiments of the invention.

In an example, the catholyte material has a protective materialoverlying exposed regions of the cathode active material to minimize areaction between the catholyte containing material and the activematerial. In an example, the protective material is configured as abarrier material. The barrier material may be AlF₃, LiF, LiAlF₄, LiPO₄,Al₂O₃, TiO₂, lithium titanate, lithium beta alumina, LiNbO₃, LiCoO₂,FeOF, FeO_(x), or other materials stable in the cathode potential range.The barrier material substantially prevents a reaction between theactive material and the catholyte material. The confinement materialsubstantially prevents an interaction of the sulfur containing specieswith an element within the major active region. The major active regionis preferably about 50 percent or more of the cathode region; and thecatholyte material is preferably about 30 percent or less of the cathoderegion. In an example, the protective material is configured toselectively allow a lithium species to traverse through the protectivematerial. As an example, the protective material may comprise aplurality of spatial openings to allow the lithium species to traversethrough the protective material. Each of the openings has a size rangingfrom about 1 nm² to about 100 nm². As another example, the protectivematerial may comprise a lithium conductive material.

Optionally, the device has a second protective material overlying eachof the plurality of active regions. The second protective material issimilar in characteristic as the first confinement material. In avariation, the protective material may be configured around the activematerial or around the ion conductive material. Alternatively, thedevice can include multiple confinement materials, among othervariations.

In an example, the catholyte comprises Li_(a)XP_(b)S_(c)O_(d) where X=Geor Si, 2≤a≤6, 0.5≤b<2.5, 4≤c≤10, and d≤3 or other variations. Furtherdetails of the LSPS material characterization can be found throughoutthe present specification and more particularly below. See, for example,the XPS, XRD, Raman, set forth herein.

In another example, the LSPS or LGPS material is characterized byLi_(a)SiP_(b)S_(c)O_(d) or Li_(a)GeP_(b)S_(c)O_(d) where 2≤a≤8,0.5≤b≤2.5, 4≤c≤12, d<3.4

In yet another example, the LSPS or LGPS material is characterized by acatholyte selected from either Li_(a)SiP_(b)S_(c) or Li_(a)GeP_(b)S_(c);wherein 2≤a≤10, 0.5≤b≤2.5, 4≤c≤12, d<3.

In an example, the catholyte material is configured to substantiallyfill the cathode region comprising the major active region to form asubstantially homogeneous thickness of material defining the cathoderegion. In an example, the catholyte material comprises a plurality ofclusters, each of which is separable. Alternatively, the catholytematerial comprises a plurality of shell structures around the activematerial particles. In other embodiments, the catholyte material isconfigured as a plurality of particles.

In an example, the catholyte material is characterized as a solid. Thatis, the material has a substantially fixed compound structure, whichbehaves like a solid rather than a fluid. In an example, the solidcatholyte material is fabricated by physical vapor deposition (PVD),chemical vapor deposition (CVD), atomic layer deposition (ALD), andsolid state reaction of powders, mechanical milling of powders, solutionsynthesis, evaporation, or any combination thereof. In an example, thecatholyte material is mixed with the active material in a mixer or millor with different configurations of physical vapor deposition,optionally mixed with carbon, and coated onto a substrate by gravure,comma coating, meyer rod coating, doctor blading, slot die coating, orwith a conventional technique. In an example, the catholyte material iscoated directly on the active material with a vapor phase growth,mechanofusion, liquid phase growth, deposition on particles in afluidized bed or rotary reactor, or combinations thereof, or the like.Of course, there are various alternatives, modifications, andvariations.

In an alternative example, the device further comprises a polymermaterial configured within a vicinity of the catholyte material, thepolymer material comprising a lithium species. The polymer material isformed overlying the catholyte material, the polymer material comprisinga lithium material. The polymer material configured to accommodate aninternal stress within the cathode region during the change in volumefrom the expansion to a contraction. An example of the polymer materialincludes polyacrylonitrile, poly-ethylene oxide, PvDF, PvDF-HFP, rubberslike butadiene rubber and styrene butadiene rubber, among others.

In an example, the silicon material has a purity of 98 to 99.9999%, thelithium has a purity of 98 to 99.9999%, phosphorous has a purity of 98to 99.9999%, and the sulfur has a purity of about 98 to 99.9999%,although there can be variations.

FIG. 4 is a simplified diagram illustrating LSPS ionic conductivityArrhenius plot according to an example of the present invention. Asshown, conductivity is plotted against 1/T. Conductivity is plotted inan Arrhenius plot. As an example, a conventional solid catholytematerial is below 10⁻⁴ S/cm for ionic conductivity, which is well belowthe present materials and techniques. Arrhenius plot of the ionicconductivity of Li_(a)GeP_(b)S_(c) and Li_(x)SiP_(y)S_(z) pressedpellets measured by electrochemical impedance spectroscopy with indiumblocking electrodes. Pellets were made by mixing 5:1:1 ratios ofLi₂S:P₂S₅:GeS₂ for Li_(a)GeP_(b)S_(e) and Li₂S:P₂S₅:SiS₂ forLi_(x)SiP_(y)S_(z) by high energy milling in a zirconia jar withzirconia media, followed by annealing at 550° C. for 8 hrs in stainlesssteel VCR Swagelok reactors. Pellets were made from the powders bypressing at 5 MPa. LXPS materials may also be synthesized by annealingin a quartz or silica reactor. LXPS may be synthesized from startingprecursors that include the elemental compounds (Li and/or and/or Siand/or P and/or Sn and/or Ge and/or S) alone or in combination with thecompounds (Li₂S, SiS₂, SnS₂, P₂S₅, GeS₂).

FIG. 5 shows LSPS and LGPS, SEM including a necking behavior indicated agood chance of forming connecting networks according to an example ofthe present invention. As shown, LGPS has features at a ten-nanometerscale, LGPS has features at a 100-nanometer scale. As shown, thematerial is configured with a plurality of particles each of which isinterconnected to each other via a necking arrangement, rather than asingle point or a “billiard ball” contact, which would limitconductivity between particles. In an example, the particle-to-neckratio dimension can be 1% to greater to 100% to form a polycrystallinestructure having a porosity of less than 30% of the total volume of thematerial. In an example, the material is substantially homogeneous in amicro-scale while configured in the polycrystalline structure in a tento one hundred micron scale. In an example, the material with activematerial, such as LiCoO₂ for example, or other variations. As shownillustrate morphology of Li_(x)SiP_(y)S_(z) and L_(a)GeP_(b)S_(c)pressed pellets. Grain sizes of these synthesized materials are 1-10 μm(synthesized by annealing Li₂S, P₂S₅, GeS₂ or SiS₂ at 550° C. for 8 hrsin stainless steel VCR Swagelok reactors). Of course, there can bevariations.

FIG. 6 shows LSPS XRD scan in air derived from material that iscrystalline from the annealing process according to an example of thepresent invention. As shown is the peak position, intensity, and FWHMdata below. As shown is XRD 2θ scan of Li_(4.4)SiP_(1.2) S_(6.3)O_(1.5)pellet. The Li_(4.4)SiP_(1.2) S_(6.3)O_(1.5) powder is synthesized byhigh energy ball milling 5:1:1 mixture of Li₂S, P₂S₅, and SiS₂ in a ZrO₂jar with ZrO₂ media, followed by annealing at 550° C. for 8 hrs instainless steel VCR Swagelok reactors. Pellets were made from thepowders by pressing at 15 MPa.

2-theta(°) d(Å) Normalized intensity FWHM(°) 26.1722 3.40207 0.16 0.567427.184 3.27771 0.45 0.2801 27.9566 3.18885 0.41 0.2701 30.9299 2.888740.12 1.5391 33.3519 2.6843 1.00 0.2044 33.8262 2.64773 0.34 2.081541.3252 2.18294 0.12 0.3451 52.1143 1.75356 0.21 0.2782 52.9999 1.726320.38 0.2964 54.6355 1.67845 0.04 0.8441 56.4607 1.62844 0.05 0.5958

FIG. 7 shows an XRD pattern and peak positions of LSPS taken in an argonenvironment according to an example of the present invention. As shownbelow are angle and height data from the XRD pattern. As shown, the LSPSmaterial is configured having a XRD pattern having a major peak along a2-theta direction and height provided in the table below and FIG. 7showing an X-ray diffraction of a Li_(5.6)SiP_(1.5) S_(6.8)O_(1.0)pressed pellet. The Li_(5.6)SiP_(1.5) S_(6.8)O_(1.0) powder issynthesized by high energy ball milling 5:1:1 mixtures of Li₂S, P₂S₅,and SiS₂ in a ZrO₂ jar with ZrO₂ media, followed by annealing at 550° C.for 8 hrs in stainless steel VCR Swagelok reactors. Pellets were madefrom the powders by pressing at 5 MPa.

2-theta(°) Normalized intensity 18.4 0.29 19.1 0.29 26.3 0.32 27.1 0.3927.9 0.39 30.1 0.42 30.9 0.55 33.4 0.43 43.8 1.00 50.4 0.41 53.1 0.44

FIG. 8 shows an LSPS XPS scan and stoichiometry including LSPS specificpeak shifts according to an example of the present invention. As shownare peaks associated with lithium, silicon, phosphorous, sulfur, andoxygen to characterize the material. Peak locations are at approximately58 eV, 104 eV, 134 eV, 164 eV, and 533 eV respectively when calibratedversus a carbon 1 s peak at 284 eV. As shown is XPS of Li_(4.4)SiP_(1.2)S_(6.3)O_(1.5) pellet. The L_(4.4)SiP_(1.2) S_(6.3)O_(1.5) powder issynthesized by high energy ball milling 5:1:1 mixture of Li₂S, P₂S₅, andSiS₂ in a ZrO₂ jar with ZrO₂ media, followed by annealing at 550° C. for8 hrs in stainless steel VCR Swagelok reactors. Pellets were made fromthe powders by pressing at 15 MPa.

FIG. 9 shows XRD patterns and peaks of several L(G)PS powders taken inan argon atmosphere according to an example of the present invention. Asshown, ratios refer to the proportion of Li₂S to P₂S₅ to GeS₂ initiallymixed to form the final compound. Actual compositions areLi_(2.85)GeP_(0.68) S₅O_(0.5) and Li_(2.2)GeP_(0.75) S₅O_(0.2). Ofcourse, there can be variations. As shown are four differentcompositions in the Figure. Compensations in the ratios 5:1:1, 45:2:1,15:2:1 are show below.

5:1:1 45:2:1 15:2:1 Li2S:P2S5:GeS2 Li2S:P2S5:GeS2 Li2S:P2S5:GeS2Normalized Normalized Normalized 2θ intensity 2θ intensity 2θ intensity12.6 0.44 16.3 0.43 12.88 0.10 14.28 0.38 15.08 0.16 15.42 0.36 28.20.70 16.12 0.26 17.06 0.38 30.7 0.73 17.87 0.14 17.62 0.43 32.24 0.7918.59 0.28 20.42 0.65 43.2 1.00 26.18 0.87 23.7 0.40 45.8 0.99 27.3 0.7024.22 0.57 48.24 0.57 30.68 1.00 25.06 0.39 52.8 0.66 31.8 0.62 25.50.39 53.96 0.80 31.88 0.80 26.9 0.62 33.7 0.17 29.24 0.45 38 0.17 29.821.00 40 0.19 31.48 0.42 42 0.26 32.74 0.53 43 0.38 33.56 0.46 45.5 0.5635.8 0.43 48.2 0.55 36.9 0.47 52.7 0.53 37.9 0.46 52.98 0.37 41.72 0.5853.5 0.34 43.2 0.65 59 0.23 47.66 0.62 51.9 0.45 52.4 0.46 52.88 0.47 540.43 55.34 0.44 55.94 0.45 57.52 0.44 58.34 0.46 59.1 0.44 60.8 0.4564.28 0.44

FIG. 10 is a plot of cyclic voltammogram of LGPS using a lithiumreference/counter electrode and stainless steel working electrode. Liplating and stripping is observed at 0 V vs. Li/Li⁺, and the lack offeatures up to 5 V indicates excellent electrochemical stability. Themeasurement is provided to indicate electrochemical stability, asindicated by the substantially straight line without peaks orimperfections. The straight line originates in an ion conductor from aplating current to form both positive and negative current as thevoltage varies from negative to positive. As shown, no significantcurrent is observed in the positive voltage region on the voltage curve,which indicates electrochemical stability: (a) Cyclic voltammogram ofLi_(7.4)GeP_(1.6) S_(9.6)O_(1.6) pressed pellet using a lithiumreference/counter electrode and stainless steel working electrode. (b)Cyclic voltammogram of Li_(5.6)SiP_(1.5) S_(6.8)O_(1.0) pressed pelletusing a lithium reference/counter electrode and Nickel foil workingelectrode. In both cases, clear Li plating and stripping occurs at 0 Vvs. Li/Li⁺.

FIG. 11 is an illustration of Raman spectroscopy signatures of severalLGPS samples. As shown, the Raman signature indicates LGPS materialconfiguration. As shown is Raman spectroscopy of variousLi_(a)GeP_(b)S_(c) pressed pellets.

Wavenumber (cm⁻¹) Normalized Intensity 202 0.22 286 0.22 383 0.53 4181.00 551 0.17 575 0.15 600 0.10 1366 0.20 1614 0.23

The Table shows Raman peaks from LGPS 15:2:1 (the ratios refer to therelative amounts of Li₂S:P₂S₅:GeS₂ precursors used in the synthesis).Note that Raman peaks shift slightly with the laser wavelength. Ofcourse, there can be other techniques to characterize the subjectmaterial. However, the Raman signature for these pellets is similar fromsample to sample.

FIG. 12 illustrates a Raman spectroscopy of LGPS, compared to itsprecursors. New features in Raman spectra can be clearly observed inLGPS versus the precursors. As shown is Raman spectroscopy of GeS₂,Li₂S, P₂S₅, and L_(a)GeP_(b)S_(c) pressed pellets. The 45:2:1 refers tothe relative amounts of Li₂S:P₂S₅:GeS₂ precursors used in the synthesis.

FIG. 13 illustrates LGPS ionic conductivity Arrhenius plot in an exampleaccording to the present invention. As shown is Arrhenius plot of theionic conductivity of various Li_(a)GeP_(b)S_(c) pressed pelletsmeasured by electrochemical impedance spectroscopy with indium blockingelectrodes. The ratios refer to the relative amounts of Li₂S:P₂S₅:GeS₂precursors used in the synthesis, while the compositions are derivedfrom X-ray photoelectron spectroscopy measurements.

FIG. 14 illustrates LGPS ionic conductivity as a function of P and Geconcentrations according to examples of the present invention. As shown,the ranges 5:1:1 to 15:2:1 and 45:2:1 are indicative of desirablematerial, and 5:1:1 is also preferred, although there can be variations.Ionic conductivity of various Li_(a)GeP_(b)S_(c) pressed pellets at 60°C. measured by electrochemical impedance spectroscopy with indiumblocking electrodes as a function of the Li₂S:P₂S₅:GeS₂ precursor ratio.

FIG. 15 illustrates composition of P and Ge in pressed pellets ofLi_(a)GeP_(b)S_(c) measured by X-ray photoelectron spectroscopy (XPS) asa function of Li₂S:P₂S₅:GeS₂ precursor ratio. As shown, decreasinggermanium and/or phosphorous content generally leads to undesirableresults. Further details of the present techniques can be foundthroughout the present specification and more particularly below.

TABLE Compositions of LGPS produced by thermal evaporation. Values areatomic percentage of each element; each row is a different sample. Ionconductivity Li Ge P S O (S/cm) at 60° C. 24.94 6.73 14.47 46.58 7.2952.02 0.10 0.23 32.46 8.06 2.5e−6 55.28 0.78 0.89 34.56 8.33  ~1e−862.75 1.92 0.11 29.93 8.11 3.5e−8 45.72 8.54 0.02 38.99 6.73  3e−6

TABLE Compositions of LSPS produced by thermal evaporation. Values areatomic percentage of each element; each row is a different sample. Ionconductivity (S/cm) at 60 Li Si P S O degrees C. 26.76 0.15 22.22 45.625.25 1e−7 5e−7

FIG. 16 shows the ion conductivity plotted as a function of temperaturefor samples according to an embodiment of the present invention. Allsamples were fabricated in a thermal evaporator with powder as thesource material. All were made from LS(G)PS powder made from milling andannealing a mixture of Li₂S, P₂S₅ and SiS₂ (GeS₂) powders. Evaporationoccurred at ˜0.1000° C. for the samples, while for other samples thetemperature was gradually increased from approximately 400 to 1500° C.during the course of the evaporation. The power was premixed accordingto the following compositions (Li₂S:P₂S₅:SiS₂):

-   -   15:2:1    -   5:1:1    -   5:1:1    -   5:1:1

The samples were, in some instances, made by thermal co-evaporation ofSiS₂ (GeS₂) powder and a mixture of Li₂S:P₂S₅ (2.5:1) powder that hadbeen milled and annealed. The sources were heated in parallel anddeposited onto a rotating substrate. The temperatures of the sourceswere increased independently as the rate of either fell.

Substrates for certain wafers were thermal oxide silicon wafer with asputtered Ti/TiN contact layer. Certain substrates were stainless steelof 4 mil thickness.

FIG. 17 is an XRD spectrum of an LSPS sample with compositionLi_(0.38)Si_(0.07)P_(0.08) S_(0.35)O_(0.12) and conductivity of 9e-4S/cm at 30° C. The peak list is presented in the following table:

2-theta(°) d(Å) Normalized intensity FWHM(°) 12.38 7.15 0.08 0.35 14.356.17 0.13 0.50 16.05 5.52 0.13 1.61 16.74 5.29 0.16 0.35 19.55 4.54 0.060.35 20.22 4.39 0.21 0.38 20.91 4.24 0.07 0.35 24.03 3.70 0.16 0.4025.27 3.52 0.21 0.15 26.94 3.31 0.35 0.28 29.10 3.07 0.30 0.20 29.673.01 1.00 0.34 31.15 2.87 0.16 0.26 31.89 2.80 0.31 1.44 32.37 2.76 0.680.20 33.42 2.68 0.19 0.43 34.12 2.63 0.09 0.35 36.81 2.44 0.09 0.3537.86 2.37 0.13 0.40 41.75 2.16 0.13 0.51 42.52 2.12 0.09 0.39 44.702.03 0.12 0.27 47.73 1.90 0.23 0.47 51.22 1.78 0.16 0.21 52.09 1.75 0.330.26 53.03 1.73 0.11 0.41

A solid-catholyte material may be fabricated by physical vapordeposition (PVD), chemical vapor deposition (CVD), atomic layerdeposition (ALD), and solid state reaction of powders, mechanicalmilling of powders, solution synthesis, evaporation, or any combinationthereof. It may then be mixed with the active material in a mixer ormill or with different configurations of physical vapor deposition,optionally mixed with carbon, and coated onto a substrate bycalendaring, doctor blading, slot die coating, or with a standardtechnique as described above. It also may be coated directly on theactive material with a vapor phase growth, liquid phase growth,deposition on particles in a fluidized bed, etc. Of course, there arevarious alternatives, modifications, and variations.

This approach enables lower cost, higher energy density batteries withbetter temperature performance, enhanced safety, and improvedelectrochemical cycling stability.

The incorporation of Si lowers the total cost of the catholyte by afactor of 10× compared to using Ge.

Use of Si in place of Ge appears to improve the stability of thecatholyte/Li interface.

A method according to an example of the present invention can beoutlined as follows:

-   -   1. Provide a substrate member;    -   2. Form a major active region comprising a plurality of first        active regions spatially disposed within a cathode region such        that the major active region expands or contracts from a first        volume to a second volume during a period of a charge and        discharge;    -   3. Form a catholyte material spatially confined within a spatial        region of the cathode region and spatially disposed within        spatial regions not occupied by the first active regions. In an        example, the catholyte material comprises a lithium, metal,        phosphorous, and sulfur (“LMPSO”) containing material configured        in a polycrystalline state;    -   4. Optionally form a protective material formed overlying        exposed regions of the cathode material to substantially        maintain the sulfur species within the catholyte material;    -   5. Form cathode active material, electron conductive additive,        binder, and other elements;    -   6. Mix cathode components together with a solvent into a slurry        and deposit the slurry on said substrate; dry the substrate    -   7. Complete solid state battery device;    -   8. Package battery device; and    -   9. Transport battery device.

The above sequence of steps is an example of a method for fabricating abattery device. In an example, steps can be combined, removed, orinclude others, among variations. Other variations, alternatives, andmodifications can exist. Further details of these process steps can befound throughout the present specification.

Certain Embodiments of the Invention Described herein.

In one example, the present invention provides an energy storage devicecomprising a cathode region, the cathode region comprising a majoractive region comprising a plurality of first active regions spatiallydisposed within the cathode region, the major active region expanding orcontracting from a first volume to a second volume during a period of acharge and discharge; a catholyte material spatially confined within aspatial region of the cathode region and spatially disposed withinspatial regions not occupied by the first active regions, the catholytematerial comprising a lithium, germanium, phosphorous, and sulfur(“LGPS”) containing material configured in a polycrystalline state; anoxygen species configured within the LGPS containing material, theoxygen species having a ratio to the sulfur species of 1:2 and less toform a LGPSO material; and a protective material formed overlyingexposed regions of the cathode material to substantially maintain thesulfur species within the catholyte material. In certain embodiments,the oxygen species is less than 20 percent of the LGPSO material. Insome embodiments, the sulfur containing species ranges from about 20 to60 percent of the LGPSO material. In other embodiments, the confinementmaterial is configured as a barrier material. In other embodiments, theconfinement material substantially prevents an interaction of the sulfurcontaining species with an element within the major active region. Inyet other embodiments, the major active region is greater than about 50percent of the cathode region; and the catholyte material is less thanabout 30 percent of the cathode region. In other embodiments, theconfinement material is configured to selectively allow a lithiumspecies to traverse through the confinement material, the confinementmaterials comprising a plurality of spatial openings to allow thelithium species to traverse through the confinement material. In yetother embodiments, the catholyte material is configured to substantiallyfill the cathode region comprising the major active region to form asubstantially homogeneous thickness of material defining the cathoderegion.

In some examples, the present invention further comprises a polymermaterial configured within a vicinity of the catholyte material, thepolymer material comprising a lithium species. In some of theseembodiments, the polymer material is formed overlying the catholytematerial, the polymer material comprising a lithium material. In otherembodiments, the polymer material configured to accommodate an internalstress within the cathode region during the change in volume from theexpansion to a contraction. In some examples, the plurality of activeregions has a size ranging from about first dimension to about a seconddimension. In some examples, the catholyte material comprising aplurality of clusters, each of which is separable. In some otherexamples, the catholyte material comprising a plurality of shellstructures. In yet other embodiments, the catholyte material isconfigured as a plurality of particles. In some examples, the presentinvention provides a device further comprising a second confinementmaterial overlying each of the plurality of active regions.

In another example, the present invention provides an energy storagedevice comprising a cathode region, the cathode region comprising: amajor active region comprising a plurality of first active regionsspatially disposed within the cathode region; a catholyte materialspatially confined within a spatial region of the cathode region andspatially disposed within spatial regions not occupied by the firstactive regions, the catholyte material comprising a lithium, germanium,phosphorous, and sulfur (“LGPS”) containing material or a lithium,silicon phosphorous, and sulfur (“LSPS”) containing material, each ofwhich is configured in a polycrystalline or amorphous state; an oxygenspecies configured within the LGPS or LSPS containing material, theoxygen species having a ratio to the sulfur species of 1:2 and less toform a LGPSO or LSPSO material; and a confinement material formedoverlying exposed regions of the cathode active material to minimizereaction between the LGPS or LSPS containing material and the activematerial. In some examples, the oxygen species ranges from less than 1percent to 20 percent of the LGPSO or LSPSO material. In other examples,the sulfur containing species ranges from about 20 to 60 percent of theLGPSO or LSPSO material. In some examples, the confinement material isconfigured as a barrier material. In yet other examples, the confinementmaterial substantially prevents an interaction of the sulfur containingspecies with an element within the major active region. In otherexamples, the major active region is greater than 50 percent by volumeof the cathode region. In certain examples, the confinement material isconfigured to selectively allow a lithium species to traverse throughthe confinement material. In other examples, the catholyte material isconfigured to substantially fill the cathode region comprising the majoractive region to form a substantially homogeneous thickness of materialdefining the cathode region.

In some examples, the devices described herein further comprise apolymer material configured within a vicinity of the catholyte material,the polymer material serving as a binder material comprising a lithiumspecies. In other examples, the polymer material is formed overlying thecatholyte material, the polymer material serving as an electrolyte. Inyet other embodiments, the polymer material is configured to accommodatean internal stress within the cathode region during the change in volumefrom the expansion to a contraction. In some other examples, the sizedistribution of active regions has a median diameter ranging from about20 nm to about 10 μm. In some examples, the catholyte materialcomprising a plurality of clusters, each of which has a median diameterranging from about 10 nm to about 300 nm. In other examples, thecatholyte material comprises a plurality of shell structures around thecathode active regions. In other examples, the catholyte material isconfigured as a plurality of particles, each of the particles having amedian diameter ranging from about 20 nm to about 300 nm. In some otherexamples, the device further comprises a second confinement materialoverlying each of the plurality of active regions. In other examples,the catholyte material is substantially free from oxygen species.

In some examples, the present invention sets forth an energy storagedevice comprising a cathode region, the cathode region comprising amajor active region comprising a plurality of first active regionsspatially disposed within the cathode region; a catholyte materialspatially confined within a spatial region of the cathode region andspatially disposed within spatial regions not occupied by the firstactive regions, the catholyte material comprising a lithium, germanium,phosphorous, and sulfur (“LGPS”) containing material or a lithium,silicon phosphorous, and sulfur (“LSPS”) containing material, each ofwhich is configured in a polycrystalline or amorphous state; a pluralityof particles characterizing the catholyte material, each of theplurality of particles is interconnected to another via a neckingarrangement, each particle having a dimension characterized by aparticle diameter to neck ratio dimension ranging from 1% to greaterthan 100% to form a polycrystalline structure having a porosity of lessthan 30% of a total volume of the cathode region. In some examples, theplurality of particles in the catholyte material is substantiallyhomogeneous in a micro-scale while configured in the polycrystallinestructure in a ten to one hundred micron scale. In other examples, thecathode region comprises an active material, the active materialcomprising iron and fluorine and/or nickel and fluorine.

In some examples, of any of the devices set forth herein, the catholytematerial is selected from one of Li_(x)SiP_(y)S_(z) orLi_(a)GeP_(b)S_(c). In some examples, the catholyte material is providedby annealing Li₂S, P₂S₅, and GeS₂ or SiS₂ at between 400-700° C. forgreater than about 4 hrs.

In some examples, of any of the devices set forth herein, the devicefurther comprises an oxygen species configured within the LGPS or LSPScontaining material, the oxygen species having a ratio to the sulfurspecies of 1:10 and less to form a LGPSO or LSPSO material; and aconfinement material formed overlying exposed regions of the cathodeactive material to minimize reaction between the LGPS or LSPS containingmaterial and the active material. In some examples, the oxygen speciesis less than 20 percent of the LGPSO or LSPSO material. In otherexamples, the sulfur containing species ranges from about 20 to 60percent of the LGPSO or LSPSO material. In certain examples, theconfinement material is configured as a barrier material. In yet otherexamples, the confinement material substantially prevents an interactionof the sulfur containing species with an element within the major activeregion. In other examples, the major active region is greater than 50percent by volume of the cathode region. In still other examples, theconfinement material is configured to selectively allow a lithiumspecies to traverse through the confinement material. In some examples,the catholyte material is configured to substantially fill the cathoderegion comprising the major active region to form a substantiallyhomogeneous thickness of material defining the cathode region. In otherexamples, the device further comprises a polymer material configuredwithin a vicinity of the catholyte material, the polymer materialserving as a binder material. In certain examples, the polymer materialis formed overlying the catholyte material, the polymer material servingas an electrolyte. In other embodiments, the polymer material isconfigured to accommodate an internal stress within the cathode regionduring the change in volume from the expansion to a contraction. In someexamples, each of the plurality of active regions has a median diameterranging from about 20 nm to about 10 μm. In some examples, each of theplurality of active regions has a median diameter ranging from about 20nm to about 3 μm. In other examples, the catholyte material comprises aplurality of clusters, the size distribution of which has a mediandiameter ranging from about 10 nm to about 300 nm. In some examples, thecatholyte material comprises a plurality of shell structures around thecathode active regions. In some examples, the catholyte material isconfigured as a plurality of particles, the size distribution of theparticles having a median diameter ranging from about 20 nm to about 300nm. In some other examples, the device further comprises a secondconfinement material overlying each of the plurality of active regions.In other examples, the catholyte material is substantially free fromoxygen species.

In some examples, the present invention sets forth an energy storagedevice comprising a catholyte material spatially confined within aspatial region of the energy storage device, the catholyte materialcomprising a lithium, germanium, phosphorous, and sulfur (“LGPS”)containing material or a lithium, silicon phosphorous, and sulfur(“LSPS”) containing material, each of which is configured in apolycrystalline, nanocrystalline or amorphous state; a room temperatureionic conductivity ranging from 10⁻⁵ to 5×10⁻² S/cm characterizing theLGPS or LSPS material; and an electrical conductivity less than 10-S/cmcharacterizing the LGPS or LSPS material. In some examples, the roomtemperature ionic conductivity ranges from 10⁻⁴ to 1e-2 S/cm; and theelectrical conductivity is less than 10⁻⁵ S/cm. In other embodiments,the device further comprises a plurality of particles characterizing thecatholyte material, each of the plurality of particles is interconnectedto another via a necking arrangement, each particle having a dimensioncharacterized by a particle diameter to neck ratio dimension rangingfrom 1% to greater than 100% to form a polycrystalline structure havinga solid area to hole area or porosity of less than 30% of a total volumeof the catholyte material. In other examples, each of the plurality ofparticles in the catholyte material is substantially homogeneous in amicro-scale while configured in the polycrystalline structure in a tento one hundred micron scale. In some examples, the cathode regioncomprises an active material, the active material comprising iron andfluorine and/or nickel and fluorine.

In some examples, the cathode region comprises an active material, theactive material comprising iron and fluorine. In some examples, thecathode region comprises an active material, the active materialcomprising nickel and fluorine.

In any of the examples, set forth herein, the catholyte material may beselected from one of Li_(x)SiP_(y)S_(z) or Li_(a)GeP_(b)S_(c). In someexamples, the catholyte material is provided by annealing Li₂S, P₂S₅,GeS₂ or SiS₂ at between 400 and 700° C. for at least 4 hrs.

In some examples, the present invention sets forth an energy storagedevice comprising a catholyte material spatially confined within aspatial region of the energy storage device, the catholyte materialcomprising: a lithium, silicon phosphorous, and sulfur (“LSPS”)containing material, each of which is configured in a polycrystalline oramorphous state; a room temperature ionic conductivity ranging from 10⁻⁵S/cm to 10⁻² S/cm characterizing the LSPS material; an electricalconductivity less than 1e-5 S/cm characterizing the LSPS material; andan XRD 2θ scan with Cu Kα radiation is characterized by a primary peakat 33°±1°, 30°±1°, or 43°±10. In some examples, the room temperatureionic conductivity ranges from 10⁻⁴ to 5×10⁻³; and the electricalconductivity range is less than 10⁻⁵ S/cm. In some examples, the devicesdescribed herein further comprise a plurality of particlescharacterizing the catholyte material, each of the plurality ofparticles is interconnected to another via a necking arrangement, eachparticle having a dimension characterized by a particle diameter to neckratio dimension ranging from 1% to greater than 100% to form apolycrystalline structure having a solid area to hole area or porosityof less than 30% of a total volume of the catholyte material. In someexamples, the plurality of particles in the catholyte material issubstantially homogeneous in a micro-scale while configured in thepolycrystalline structure in a ten to one hundred micron scale. In someother examples, the catholyte material comprises an active material, theactive material comprising iron and fluorine and/or nickel and fluorine.In certain examples, the catholyte material is selected from one ofLi_(x)SiP_(y)S_(z) or Li_(a)GeP_(b)S_(c). In some other examples, thecatholyte material is provided by annealing Li₂S, P₂S₅, GeS₂ or SiS₂ atbetween 400-700° C. for at least 4 hrs.

In some examples, the present invention sets forth an energy storagedevice comprising a catholyte material spatially confined within aspatial region of the energy storage device, the catholyte materialcomprising a lithium, silicon phosphorous, and sulfur (“LSPS”)containing material, each of which is configured in a polycrystalline oramorphous state; a room temperature ionic conductivity ranging from 10⁻⁵S/cm to 10⁻² S/cm characterizing the LSPS material; an electricalconductivity less than 1e-5 S/cm characterizing the LSPS material; andan XRD 2θ scan with Cu Kα radiation is characterized by a first majorpeak between about 41 to 45° 2θ and a second major peak between about 30to 35° 2θ and a third major peak between 51-54° 2θ. In some examples,the first major peak is higher in intensity than either the second majorpeak or the third major peak. In other examples, the XRD is measured incounts per second and the first major peak is higher in intensity thaneither the second major peak or the third major peak. In yet otherexamples, the device exhibits a cyclic voltammogram characterized by acurrent density of less than 1 mA/cm² when the voltage is swept at 10mV/s between 0.1-4.5V vs Li/Li⁺ and the sample is maintained at 30° C.

In some examples, the present invention sets forth an energy storagedevice comprising a cathode region, the cathode region comprising amajor active region comprising a plurality of first active regionsspatially disposed within the cathode region, the major active regionexpanding or contracting from a first volume to a second volume during aperiod of a charge and discharge; a catholyte material spatiallyconfined within a spatial region of the cathode region and spatiallydisposed within spatial regions not occupied by the first activeregions, the catholyte material comprising a lithium, germanium,phosphorous, and sulfur (“LGPS”) containing material configured in apolycrystalline state; wherein the catholyte material is characterizedby an XRD as measured in counts per second characterized by a firstmajor peak between at 41 to 45° 2θ, between about 30 to 35° 2θ;whereupon the first major peak is higher in intensity than either thesecond major peak or the third major peak. In some examples, the devicefurther comprises an oxygen species configured within the LGPScontaining material, the oxygen species having a ratio to the sulfurspecies of 1:2 and less to form a LGPSO material wherein the oxygenspecies is less than 20 percent of the LGPSO material. In otherexamples, the sulfur containing species ranges from about 25 to 60percent of the LGPSO material. In certain examples, the device furthercomprises a confinement material formed overlying exposed regions of thecathode material to substantially maintain the sulfur species within thecatholyte material; wherein the confinement material is configured as abarrier material. In certain other examples, the device furthercomprises a confinement material; wherein the confinement materialsubstantially prevents an interaction of the sulfur containing specieswith an element within the major active region. In other examples, themajor active region is greater than about 50 percent by volume of thecathode region; and the catholyte material is less than about 30 percentby volume of the cathode region. In other examples, the device furthercomprises a confinement material; wherein the confinement material isconfigured to selectively allow a lithium species to traverse throughthe confinement material, the confinement materials comprising aplurality of spatial openings to allow the lithium species to traversethrough the confinement material. In other examples, the catholytematerial is configured to substantially fill the cathode regioncomprising the major active region to form a substantially homogeneousthickness of material defining the cathode region. In yet otherexamples, the device further comprises a polymer material configuredwithin a vicinity of the catholyte material, the polymer materialcomprising a lithium species. In other examples, the polymer material isformed overlying the catholyte material, the polymer material comprisinga lithium material. In other examples, the polymer material configuredto accommodate an internal stress within the cathode region during thechange in volume from the expansion to a contraction. In still otherexamples, each of the plurality of active regions has a size rangingfrom about first dimension to about a second dimension. In some otherexamples, the catholyte material comprises a plurality of clusters, eachof which is separable. In other examples, the catholyte materialcomprises a plurality of shell structures. In other examples, thecatholyte material is configured as a plurality of particles. In someother examples, the device further comprises a second confinementmaterial overlying each of the plurality of active regions.

In some examples, the present invention sets forth a method formanufacturing an energy storage device comprising forming a cathoderegion, the cathode region comprising a major active region comprising aplurality of first active regions spatially disposed within the cathoderegion, the major active region expanding or contracting from a firstvolume to a second volume during a period of a charge and discharge; acatholyte material spatially confined within a spatial region of thecathode region and spatially disposed within spatial regions notoccupied by the first active regions, the catholyte material comprisinga lithium, germanium, phosphorous, and sulfur (“LGPS”) containingmaterial configured in a polycrystalline state. In some examples, theLGPS containing material comprises an oxygen species configured withinthe LGPS containing material, the oxygen species having a ratio to thesulfur species of 1:2 and less to form a LGPSO material. In some otherexamples, the method further comprises forming a confinement materialformed overlying exposed regions of the cathode material tosubstantially maintain the sulfur species within the catholyte material.In still other examples, the oxygen species is less than 20 atomicpercent of the LGPSO material. In other examples, the sulfur containingspecies ranges from about 25 to 60 percent of the LGPSO material. Insome other examples, the method further comprises forming a confinementmaterial configured as a barrier material. In still other examples, theconfinement material substantially prevents an interaction of the sulfurcontaining species with an element within the major active region. Inyet other examples, the major active region is at least 50 percent byvolume of the cathode region; and the catholyte material is less thanabout 30 percent by volume of the cathode region. In some otherexamples, the method further comprises forming a confinement materialconfigured to selectively allow a lithium species to traverse throughthe confinement material, the confinement materials comprising aplurality of spatial openings to allow the lithium species to traversethrough the confinement material. In other examples, the catholytematerial is configured to substantially fill the cathode regioncomprising the major active region to form a substantially homogeneousthickness of material defining the cathode region. In other examples,the method further comprises forming a polymer material configuredwithin a vicinity of the catholyte material, the polymer materialcomprising a lithium species. In some other examples, the polymermaterial is formed overlying the catholyte material, the polymermaterial comprising a lithium material. In yet other examples, thepolymer material configured to accommodate an internal stress within thecathode region during the change in volume from the expansion to acontraction. In some other examples, each of the plurality of activeregions has a size ranging from about first dimension to about a seconddimension. In still other examples, the catholyte material comprises aplurality of clusters, each of which is separable. In some examples, thecatholyte material comprises a plurality of shell structures. In yetother examples, the catholyte material is configured as a plurality ofparticles. In yet other examples, the method further comprises a secondconfinement material overlying each of the plurality of active regions.

In some examples, the present invention sets forth a solid catholytematerial comprising a lithium element; a silicon element; a phosphorouselement; a sulfur element; and an oxygen element; wherein the major peakis located at a peak in a position of 2θ=30°±1° in an X-ray diffractionmeasurement using a CuKα line, or at the peak of 2θ=33°±1° or a peak of2θ=43°±1°. In some embodiments, the present invention provides a solidion conducting material characterized by a formulaLi_(a)SiP_(b)S_(c)O_(d) where 2≤a≤8, 0.5≤b≤2.5, 4≤c≤12, d<3, wherein anyimpurities are less than 10 atomic percent. In some examples, thepresent invention provides a solid ion conducting material comprisingLi, Si, P, and S characterized by primary Raman peaks at 418±10 cm⁻¹,383±10 cm⁻¹, 286±10 cm⁻¹, and 1614±10 cm⁻¹ when measured by a RenishawinVia Raman microscope. In yet other examples, the present inventionprovides a solid ion conducting material that results from a reaction ofx Li₂S, y SiS₂, and z P₂S₅, where 1≤x/y≤50 and 0.5≤z/y≤3.

In some examples, the present invention sets forth a process formanufacture of a solid ion conducting material comprising the steps ofmixing Li₂S, P₂S₅, and SiS₂ and then heating the mixture to atemperature above 400° C. for a time of greater than 3 hours.

According to an embodiment of the present invention, techniques relatedto a solid catholyte material having desired ion conductivity areprovided. More particularly, an embodiment of the present inventionpresent invention provides a method and structure for a catholytematerial to improve a total ionic conductivity for a cathode to allowfor higher mass loading of an active material, faster charge/discharge,and a wider range of operating temperature. Merely by way of example,the invention has been applied to solid state battery cells, althoughthere can be other applications.

As background, poor ionic conductivity of the cathode active material ina battery imposes strong limitations to overall performance,particularly in an all solid state battery wherein a solid catholytematerial is needed to enable transport of ions from the cathode to theelectrolyte. By mixing the low ionic conductivity cathode activematerial with a high ionic conductivity ceramic catholyte, we canimprove overall cathode conductivity. Rate capability in a battery canbe improved by increasing the volume fraction of the catholyte material.To improve electronic conductivity to match the ionic conductivity, adopant species such as carbon can be added as a third component orpre-coated onto the cathode active material. Depending on theimplementation, dopant species can be selected from a tin element, analuminum element, carbon, titanium, hafnium, cerium, and/or zirconium.

In an example, an embodiment of the present invention sets forth a solidstate catholyte, lithium-silicon-tin-phosphorus-sulfide (LSTPS), whichpossesses Li ion conductivity of >5×10⁻³ S/cm at 60° C. The compositionof the catholyte is Li_(a)Si_(b)Sn_(c)P_(d)S_(e). LSTPS is synthesizedusing starting precursor materials: Li₂S, P₂S₅, Si, Sn, and S by a solidstate reaction procedure wherein the materials are milled together andannealed to form a crystal line material.

In an example, the high ionic conductivity solid state catholyte enablesimproved energy density, power density, and low temperature performanceof a battery with improved safety by eliminating the use of typicalflammable components. Examples of conventional techniques are described.

That is, conventional cation ceramic sulfide ionic conductors have beenproposed. These materials contain up to three cations paired with asulfur anion. These materials may be amorphous or crystalline. Thesematerials do not utilize an advantageous doping effect of a fourthcation, which limits the achievable ionic conductivity. Examples in theliterature include: Kamaya et al., A lithium super ionic conductor, Nat.Mat. 10 (2011) 682-686. DOI: 10.1038/NMAT3066, and Murayama, et al.,Material design of new lithium ionic conductor, thio-LISICON, in the Li₂ S-P-S ₅ system, Solid State Ionics 170 (2004) 173-180. DOI:10.1016/j.ssi.2004.02.025.

Conventional ceramic oxide ionic conductors have also been proposed.These ceramic oxide ionic conductors contain multiple cations pairedwith an oxygen anion. These materials cannot be used as catholytematerials since the space-filling requirement of the catholytemorphology needed to achieve high volumetric and gravimetric energydensity necessitates a tortuous and highly granular structure with ahigh surface area to volume ratio. In the case of these oxides, highgrain boundary impedances severely limit overall ionic conductivity,which are difficult to mitigate without high temperature sintering inexcess of 1000° C. Such conditions can damage other components of thecell architecture. Examples include:

-   Buschmann, et al. Lithium metal electrode kinetics and ionic    conductivity of the solid lithium ion conductors “Li ₇ La ₃ Zr ₂ O    ₁₂ ” and Li _(7-x) La ₃ Zr _(2-x) Ta _(x) O ₁₂. J. Power Sources    206 (2012) 236-244. DOI: 10.1016/j.jpowsour.2012.01.094; and-   Ohta, et al. High lithium ionic conductivity in the garnet-type    oxide Li _(7-x) La ₃(Zr _(2-x) Nb _(x))O ₁₂ (x=0-2). J. Power    Sources 196 (2011) 3342-3345. DOI: 10.1016/j.jpowsour.2010.11.089.

Conventional liquid ionic conductors have also been proposed. Thesematerials typically consist of an ionic salt solvated in a liquid phase.These conductors often suffer from voltage instability. This voltageinstability manifests in the formation of a solid electrode interface(SEI), which requires costly formation cycling and initial charge loss.Also extremely detrimental is the inherent flammability of theseliquids, which severely impacts the overall safety of the device.

In an example, the composite ceramic catholyte material with chemicalformula Li_(a)X_(b)P_(c)S_(d) (LX(=M)PS), where X can be Ge, Si, Sn, orany combination thereof, may be synthesized using a solid statereaction. The precursors include Li₂S, P₂S₅, an elemental powder of X,and S. The powders are mixed in a ratio L_(a)X_(b)P_(c)S_(d) where a=5,b=1, c=1, and d=2. In the case of LSPS, LTPS, or LGPS, b=1, and X iselemental Si powder (LSPS), elemental tin powder (LTPS), or elementalgermanium powder (LGPS). In a non-limiting example of LSTPS, thecomposition Li_(a)Si_(b)Sn_(c)P_(d)S_(e), where a=5, b=0.5, c=0.5, d=1,and e=2. The precursor powders are exposed to high energy planetarymilling, followed by annealing in enclosed reactors at 550° C. for 8hours. The catholyte is then mixed with a binder, an active electrodematerial and an electronic conductor to form a composite positiveelectrode material, as illustrated in FIG. 18A. The positive electrodeis then assembled into a fully functional solid state device, asillustrated in FIG. 18B.

FIG. 18A is a simplified illustration of an electrode material(including an active positive electrode material, ionic conductor,binder, and electronic conductor) according to an example of the presentinvention. The LMPS material forms a percolating network throughout thecathode and conducts ions to the active material with low transportlosses.

FIG. 18B is a simplified illustration of a negative electrode currentcollector, a solid state electrolyte, and a positive electrode currentcollector according to an example of the present invention.

To assess ionic conductivity, the LXPS powders are pressed into pelletsand studied using electrochemical impedance spectroscopy with blockingelectrodes. The ionic conductivity of 4 component materials ranks inorder of LGPS>LSPS>LTPS, as shown in FIG. 19, where average ionicconductivity of both LGPS and LSPS exceed 1×10⁻³ S/cm at 60° C. It isunexpectedly shown that addition of a dopant material to create LSTPSimproves the conductivity by a factor of 2× relative to average LSPS and10× relative to average LTPS. Champion samples of LSTPS possessconductivities in excess of 5×10⁻³ S/cm at 60° C. In an example, theconductivity of LSTPS exceeds the conductivity of any of the 4-componentmaterials, and LSTPS is substantially less expensive than LGPS, sincethe cost of Ge is many times higher than the cost of Sn or Si.

Certain examples of the present invention surprisingly show that mixedSi/Sn doping unexpectedly results in beneficial conductivity properties.

In addition, the doped LSTPS material possesses an activation energy of0.25 eV, lower than either LSPS (0.26 eV) or LTPS (0.28 eV), aspreviously shown in FIG. 20.

The conductivity trend extends down to 10° C. without the appearance ofany additional grain boundary impedance, demonstrating the uniqueability of sulfide materials to achieve excellent inter-grain contactwithout the need for high temperature sintering, unlike many oxidematerials.

XRD shows that all of the materials possess a unique crystallinestructure shown in FIG. 21. That is, FIG. 21 illustrates crystalstructure from XRD spectra of LSTPS, LSPS, and LTPS according toexamples according to the present invention.

XPS compositions in TABLE A confirm that LSTPS contains a mixture ofboth Si & Sn, whereas LSPS contains no Sn, and LTPS contains no Si. Inan example, the composition range of LSPS includesLi_(a)SiP_(b)S_(c)O_(d) where 2≤a≤12, 0.5≤b≤3, 2≤c≤15, and 0≤d≤2. Thecomposition range of LTPS includes Li_(a)SnP_(b)S_(c)O_(d) where 2≤a≤12,0.5≤b≤3, 2≤c≤15, and 0≤d≤3. The composition range of LSTPS includes30-50 at % Li, 0-10 at % Si, 0-10 at % Sn, 5-15 at % P, 30-55 at % S,and 0-15 at % O.

TABLE A Compositions based on XPS analysis ID Li O P S Si Sn LSTPS 43 89 34 4 2 LTPS 36 11 13 34 0 6 LSPS 42 6 9 34 10 0

In an example, the unique chemical environments of the Li & P atomsbetween the LXPS compositions are shown in ⁷Li NMR spectra of FIGS. 22A,22B, 22C, and 22D and ³¹P NMR spectra of FIGS. 23A, 23B, 23C, and 23D.Table B below provides an example of chemical environment based on ⁷Liand ³¹P NMR analysis. In an example, the peak shifts are listed in TableB.

TABLE B Chemical environments based on ⁷Li and ³¹P NMR analysis ⁷Li peakshifts (ppm) ³¹P peak shifts (ppm) LSPS 1.176 73.217 87.114 93.892 LSTPS0.732 75.575 86.699 93.590 108.367 LTPS 0.812 77.418 92.733 108.360 LGPS0.955 74.430 86.590 92.227 109.251

TABLE C XRD peak positions of LSTPS Pos. Height FWHM Left d-spacing Rel.Int. [°2Th.] [cts] [°2Th.] [Å] [%] 12.733610 26.591680 0.157440 6.952075.73 14.784530 56.879290 0.157440 5.99197 12.25 17.723710 38.5584200.236160 5.00437 8.31 20.481290 143.921600 0.118080 4.33640 31.0120.781580 133.582900 0.118080 4.27441 28.78 24.229180 111.1745000.137760 3.67345 23.95 27.243660 158.124100 0.196800 3.27345 34.0727.763790 43.883490 0.236160 3.21329 9.45 29.354880 76.615600 0.1574403.04265 16.51 29.856440 464.168600 0.177120 2.99267 100.00 31.96592035.157160 0.196800 2.79983 7.57 33.639830 54.079900 0.157440 2.6642411.65 35.873710 31.241780 0.236160 2.50330 6.73 36.919290 99.5918700.157440 2.43477 21.46 37.924850 48.159920 0.236160 2.37249 10.3841.732860 141.007900 0.196800 2.16439 30.38 42.569990 84.150730 0.2755202.12375 18.13 45.560390 42.126310 0.236160 1.99107 9.08 47.630040206.606000 0.236160 1.90928 44.51 49.299420 29.497720 0.393600 1.848466.35 51.935750 46.042590 0.236160 1.76066 9.92 52.798970 56.4378600.314880 1.73390 12.16 55.107590 25.241580 0.472320 1.66660 5.4455.994610 36.691830 0.314880 1.64228 7.90 58.343510 49.514790 0.3148801.58164 10.67 59.193100 26.718480 0.314880 1.56095 5.76 60.39877033.454870 0.314880 1.53265 7.21 64.457960 27.037480 0.314880 1.445595.82 71.353960 9.812757 0.551040 1.32187 2.11 72.420560 11.3358600.472320 1.30501 2.44FIG. 24 illustrates a schematic of full cell with solid state catholytein an example according to the present invention. In an example, theLMPS material is present in the cathode as the ion conductor providingion transport to the active material throughout the cathode.

FIG. 25 is an SEM micrograph of cast film of solid state LMPS accordingto an example of the present invention.

In contrast to previous efforts to synthesize a sulfide-based ionicconductor, the addition of N cation dopants (where N=1, 2, 3 . . . )further improves the ionic conductivity of the material relative to theN-1 composition. This is highlighted by the LSTPS composition, in whichthe conductivity exceeds both LSPS and LTPS, and additionally possesseslower activation energy than both LSPS and LTPS. The improvedconductivity and shallower activation energy enables higher energydensity, power density, and low temperature performance of a battery,while also possessing the non-flammability (improved safety) of an allsolid state ionic conductor.

A method according to an example of the present invention can beoutlined as follows:

1. In an example, powders of Li₂S, P₂S₅, elemental Si, elemental Sn, andelemental S are mixed in a 5:1:0.5:0.5:2 mol ratio to produce LSTPS.Powders of Li₂S, P₂S₅, SiS₂, SnS₂ are mixed in a 5:1:0.5:0.5 mol ratioto produce LSTPS in an example, while there can be variations. Powdersof Li₂S, P₂S₅, elemental Sn, and elemental S are mixed in a 5:1:1:2 molratio to produce LTPS in an example. Powders of Li₂S, P₂S₅, and SnS₂ aremixed in a 5:1:1 mol ratio to produce LTPS in an example. Powders ofLi₂S, P₂S₅, elemental Si, and elemental S are mixed in a 5:1:1:2 molratio to produce LSPS In an example. Powders of Li₂S, P₂S₅, and SiS₂ aremixed in a 5:1:1 mol ratio to produce LSPS in an example. Powders ofLi₂S, P₂S₅, elemental Ge, and elemental S are mixed in a 5:1:1:2 molratio to produce LGPS in an example. Powders of Li₂S, P₂S₅, and GeS₂ aremixed in a 5:1:1 mol ratio to produce LGPS in an example. In an example,P₂S₅ can be replaced with a 2:5 mixture of elemental P and elemental S.In an example, the molar equivalent of Li₂S can be as low as 4.5 and ashigh as 5.5. In an example, the molar equivalent of P₂S₅ can be as lowas 0.6 and as high as 1.4. In an example, the Si/(Si+Sn) stoichiometrycan be as low as 0.25 and as high as 0.75. Of course, there can bevariations in compositions, times, and other parameters. Depending onthe specific process performed, the mixing ratios may be changed due tomaterial loss and/or other factors.

2. The mixture of powder from Step 1 is loaded into, for example, a50-500 ml milling jar containing 1-10 mm spherical milling media. Themilling jar and media could be composed of stainless steel, hardenedsteel, alumina, or zirconia, in an example. In an example, 14 gr. of themixture from Step 1 is loaded into a 50 ml ZrO₂ milling jar containing50 gr. of 1 mm ZrO₂ spherical milling media.

3. The mixture in the milling jar is milled. In an example, the mixtureis milled at 200-400 rpm for 4-16 hours in a planetary mill, althoughthere can be variations, with 400 rpm for 8 hours being one preferredexample. In another example, a shaker mill could be used.

4. The powder in the milling jars from Step 3 is recovered using asieve, preferably 80 mesh, in an example.

5. The powder after sieving in Step 4 is loaded into an enclosedreactor. This reactor can be a vacuum sealed quartz tube or a highpressure and high temperature autoclave constructed of steel in anexample.

6. The reactor vessel is heated to 400-700° C. for a soak duration of1-8 hours.

7. The powder after annealing in Step 6 is recovered from the reactorvessel and finely distributed using a mortar & pestle, additionalplanetary milling, or vortex milling in an example.

8. The powder from Step 7 can be further downsized as needed using aplanetary mill, a media mill, or a jet mill in order to achieve betterpercolation in a cathode in an example.

9. The powder derived from either Step 7 or Step 8 is then mixed with anactive material to form a full cathode.

10. The cathode can then be assembled with an electrolyte and anode tocreate a full cell, in an example.

The above sequence of steps is an example of a method for fabricating abattery device. In an example, steps can be combined, removed, orinclude others, among variations. Other variations, alternatives, andmodifications can exist.

In an example, a doped LSPS material is provided. In an example, theLSPS material comprises a lithium species, a silicon species, aphosphorous species, and a sulfur species. In an example, the doped LSPSmaterial is configured with a plurality of dopant species consisting ofa tin species to form an LSTPS alloy material; wherein the lithiumspecies ranges from 30 to 50 at %; wherein the silicon species rangesfrom 0 to 15 at %; wherein the tin species ranges from 0 to 15 at %; thephosphorous species ranges from 5 to 17 at %; the sulfur species rangesfrom 30-55 at %; and the oxygen species ranges from 0-15 at %.

In an example, a doped LGPS material comprising a lithium species, agermanium species, a phosphorous species, and a sulfur species isprovided. The doped LGPS material is doped with a plurality of tinspecies to form an LGTPS alloy material; wherein the lithium speciesranges from 30 to 50 at %; wherein the germanium species ranges from 0to 15 at %; wherein the tin species ranges from 0 to 15 at %; thephosphorous species ranges from 5 to 17 at %; the sulfur species rangesfrom 30 to 55 at %. In an example, the doped LGPS material furthercomprises an oxygen species ranging from 0-15 at %.

In an alternative example, a doped LGPS material comprising a lithiumspecies, a germanium species, a phosphorous species, and a sulfurspecies is provided. In an example, the doped LGPS material isconfigured with a plurality of dopant species to form an LGSPS alloymaterial; wherein the lithium species ranges from 30 to 50 at %; whereinthe germanium species ranges from 0 to 15 at %; wherein the siliconspecies ranges from 0 to 15 at %; the phosphorous species ranges from 5to 17 at %; the sulfur species ranges from 30 to 55 at %; and the dopedLGPS material. The doped LGPS material further comprises an oxygenspecies ranging from 0-15 at %.

In an alternative example, a doped LMPS material characterized with aplurality of different XRD peaks in a plurality of ranges including18-21°, 26-28°, 28-31°, and 46-48° is provided. In an alternativeexample, a doped LMPS material characterized with at least one ⁷Li NMRpeak shifts ranging from 0.5-1.5 ppm is provided. In an alternativeexample, a doped LMPS material characterized with at least one ³¹P NMRpeak shifts ranging from 86-88 ppm (LSPS, LGPS, LSTPS), 92-94 ppm(LSTPS, LTPS, LGPS), 74-78 ppm (LSTPS, LTPS, LGPS), or 108-109 ppm(LTPS, LSTPS) is provided.

Although numerous examples of the invention have been illustrated anddescribed, the invention is not so limited. Numerous modifications,variations, substitutions and equivalents will occur to those skilled inthe art without departing from the spirit and scope of the presentinvention.

While the above is a full description of the specific embodiments,various modifications, alternative constructions and equivalents may beused. Therefore, the above description and illustrations should not betaken as limiting the scope of the present invention which is defined bythe appended claims.

What is claimed:
 1. An energy storage device comprising a cathoderegion, the cathode region comprising: an active material regioncomprising an active material that expands or contracts from a firstvolume to a second volume during a period of charge and discharge; acatholyte material spatially confined in spatial regions not occupied bythe active material region, wherein the catholyte material comprises: alithium element; a member selected from the group consisting of asilicon element, tin element, germanium element, and combinationsthereof; a phosphorous element; a sulfur element; and an oxygen element,wherein the catholyte material is characterized by a primary CuKα XRDpeak at 2θ=30°±1°, 2θ=33°±1°, or 2θ=43°±1°, and wherein the oxygenelement has a ratio to the sulfur element of 1:2 or less to form aLGPSO, LSPSO, or LTPSO material; and optionally, a protective materialoverlying exposed regions of the active material to substantiallymaintain the sulfur element within the catholyte material.
 2. The deviceof claim 1, wherein the oxygen element is less than 20 atomic percent ofthe LGPSO, LSPSO, or LTPSO material.
 3. The device of claim 1, whereinthe active material region is greater than about 50 percent by volume ofthe cathode region, and wherein the catholyte material is less thanabout 30 percent by volume of the cathode region.
 4. The device of claim1, wherein the active material region is greater than about 45 percentby volume of the cathode region, and wherein the catholyte material isless than about 30 percent by volume of the cathode region.
 5. Thedevice of claim 1, further comprising a polymer material configuredwithin a vicinity of the catholyte material.
 6. The device of claim 1,wherein the catholyte material comprises a plurality of particles. 7.The device of claim 1, wherein the active material region comprisesclusters having a median diameter ranging from about 2 μm to about 10μm.
 8. The device of claim 1, wherein the catholyte material comprises aplurality of particles interconnected via a necking arrangement, andwherein the particle diameter to neck ratio dimension ranges from 1% togreater than 100% to form a polycrystalline structure having a porosityof less than 30% of a total volume of the cathode region.
 9. The deviceof claim 1, wherein the active material comprises iron and fluorine. 10.The device of claim 1, wherein the active material is selected from NCA(nickel cobalt aluminum oxide), LMNO (lithium manganese nickel oxide),LCO (lithium cobalt oxide), nickel fluoride (NiF_(x), wherein x is from0 to 2.5), iron fluoride (FeF_(z), wherein z is from 0 to 3), and copperfluoride (CuF_(y), wherein y is from 0 to 2.5).
 11. The device of claim1, wherein the catholyte material is selected fromLi_(a)SiP_(b)S_(c)O_(d) and Li_(a)GeP_(b)S_(c)O_(d), wherein 2≤a≤10,0.5≤b≤2.5, 4≤c≤12, and d≤3.
 12. The device of claim 1, wherein thecatholyte material is Li_(a)GeP_(b)S_(c)O_(d), wherein 2≤a≤10,0.5≤b≤2.5, 4≤c≤12, and d≤3.4.
 13. The device of claim 1, wherein theoxygen element has a ratio to the sulfur element of 1:10 or less. 14.The device of claim 1, wherein the active material region is greaterthan 50 percent by volume of the cathode region.
 15. The device of claim1, wherein the catholyte material has a room temperature ionicconductivity ranging from 10⁻⁵ to 5×10⁻² S/cm and an electricalconductivity less than 10⁻⁵ S/cm.
 16. The device of claim 15, whereinthe room temperature ionic conductivity ranges from 10⁻⁴ to 10⁻² S/cm.17. The device of claim 1, wherein the catholyte material is the LSPSOmaterial and is characterized by: a room temperature ionic conductivityranging from 10⁻⁵ S/cm to 10⁻² S/cm; and an electrical conductivity lessthan 10⁻⁵ S/cm.
 18. The device of claim 1, wherein the catholyte is theLSPSO material and is characterized by: a room temperature ionicconductivity ranging from 10⁻⁵ S/cm to 10⁻² S/cm; an electricalconductivity less than 10⁻⁵ S/cm; and a first major CuKα XRD peakbetween about 41 to 45° 2θ, a second major CuKα XRD peak between about30 to 35° 2θ, and a third major CuKα XRD peak between 51-54° 2θ.
 19. Thedevice of claim 1, wherein the catholyte material isLi_(a)SiP_(b)S_(c)O_(d), wherein 2≤a≤10, 0.5≤b≤2.5, 4≤c≤12, and d≤3, andwherein any impurities are less than 10 atomic percent.
 20. The deviceof claim 1, wherein the catholyte material is characterized by primaryRaman peaks at 418±10 cm⁻¹, 383±10 cm⁻¹, 286±10 cm⁻¹, and 1614±10 cm⁻¹when measured by a Renishaw inVia Raman microscope.
 21. The device ofclaim 1, wherein the catholyte material is the LSPSO material doped witha tin element to form an LSTPSO alloy material, wherein the lithiumelement ranges from 30 to 50 at %, wherein the silicon element rangesfrom 0 to 15 at %, wherein the tin element ranges from 0 to 15 at %,wherein the phosphorous element ranges from 5 to 17 at %, wherein thesulfur element ranges from 30-55 at %, and wherein the oxygen elementranges from 0-15 at % of the catholyte material.
 22. The device of claim1, wherein the catholyte material is the LMPSO material doped with adopant and characterized by a plurality of different XRD peaks in aplurality of ranges including 18-21°, 26-28°, 28-31°, 40-42°, and46-48°.
 23. The device of claim 1, wherein the catholyte material ischaracterized by at least one ⁷Li NMR peak shift ranging from 0.5-1.5ppm.
 24. The device of claim 1, wherein the catholyte material ischaracterized by at least one ³¹P NMR peak shifts ranging from 86-88ppm, 92-94 ppm, 73-78 ppm, or 108-109.5 ppm.